46 MIMICRY, AND OTHER PROTECTIVE 



propounded by MacLeay, and developed by Swainson, 

 with an amount of knowledge and ingenuity that 

 have rarely been surpassed. This theory was emi- 

 nently attractive, both from its symmetry and com- 

 pleteness, and from the interesting nature of the 

 varied analogies and affinities which it brought to 

 light and made use of. The series of Natural His- 

 tory volumes in " Lardner's Cabinet Cyclopaedia," 

 in which Mr. Swainson developed it in most de- 

 partments of the animal kingdom, made it widely 

 known ; and in fact for a long time these were 

 the best and almost the only popular text-books for 

 the rising generation of naturalists. It was favour- 

 ably received too by the older school, which was 

 perhaps rather an indication of its unsoundness. A 

 considerable number of well-known naturalists either 

 spoke approvingly of it, or advocated similar princi- 

 ples, and for a good many years it was decidedly 

 in the ascendent. With such a favourable introduc- 

 tion, and with such talented exponents, it must have 

 become established if it had had any germ of truth 

 in it; yet it quite died out in a few short years, 

 its very existence is now a matter of history ; and so 

 rapid was its fall that its talented creator, Swainson, 

 perhaps lived to be the last man who believed in it. 



Such is the course of a false theory. That of a 

 true one is very different, as may be well seen by 

 the progress of opinion on the subject of Natural 

 Selection. In less than eight years "The Origin of 

 Species " has produced conviction in the minds of 



